hydroxychloroquine

Hydroxychloroquine (Plaquenil) can cause severe and life-threatening heart rhythm problems, including a severe heart rhythm problem called QT prolongation. Your risk for QT prolongation is higher if you have certain factors, including abnormal electrolyte levels and heart rhythm problems. Your risk is also higher if you're taking other medications that cause heart rhythm problems, such as amiodarone (Pacerone) and quetiapine (Seroquel), among others. If you feel your chest pounding, have shortness of breath, have chest pain, or feel faint or lightheaded while taking hydroxychloroquine (Plaquenil), call 911 right away.

Hydroxychloroquine (Plaquenil) can affect how well phospholipids (a type of fat) are processed in your body. This can lead to a condition called drug-induced phospholipidosis, where there's a build-up of phospholipids that can damage some of your organs and cause symptoms. Examples include:

Although rare, hydroxychloroquine (Plaquenil) can cause vision changes, including blurry vision and complete vision loss. This happens because the medication can damage the retina of the eye. Ask your provider if you need regular eye exams while on hydroxychloroquine (Plaquenil). Additionally, report any vision changes to your provider immediately so you can be tested.

Severe allergic reactions to hydroxychloroquine (Plaquenil) are possible, including life-threatening reactions like facial swelling and anaphylaxis (e.g., closing of the throat). Hydroxychloroquine (Plaquenil) can also cause serious skin reactions (e.g., Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN)) If you notice changes in your skin (e.g., sore throat, fever, fatigue, rash, painful blisters, skin reddening, skin peeling), stop using hydroxychloroquine (Plaquenil) and get medical attention right away.

Hydroxychloroquine (Plaquenil) can lower the number of red blood cells (RBCs), white blood cells (WBCs), and platelets in your body. This can raise your risk for bleeds, anemia, and infections. Your provider might order blood draws to check your blood cell counts. Let your provider know if you experience possible symptoms of low blood cell counts, such as:

Hydroxychloroquine (Plaquenil) can cause red blood cells to break down (hemolytic anemia) in people with a certain genetic condition. Your provider will monitor your blood cell counts before and during treatment. Contact your provider if you experience symptoms such as tiredness, dizziness, and weakness.

Some people reported suicidal thoughts or thoughts of self-harm while taking hydroxychloroquine (Plaquenil). If you or anyone around you notice that you have suicidal thoughts or unusual behavior (e.g., anxiety, panic attacks, difficulty sleeping, feeling angry or irritated, restlessness) while taking hydroxychloroquine (Plaquenil), get medical help right away.

Hydroxychloroquine (Plaquenil) can cause dangerously low blood sugar levels. If you already have diabetes, your provider might ask you to check your blood sugar levels more often. It's best to carry with you some form of fast-acting sugar (e.g., glucose tablets, hard candy, fruit juice) at all times while you're taking this medication because you can use these to raise your blood sugar quickly if it becomes too low. If you experience symptoms of low blood sugar (e.g., shakiness, anxiety, unusual hunger or thirst, confusion), take 15 grams of fast-acting sugars and check your blood sugar levels in 15 minutes. If your blood sugar levels don't go back up, get medical help right away and take more fast-acting sugars while you wait for help to arrive.